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authorMichał Masłowski <mtjm@mtjm.eu>2014-09-03 14:30:21 (EDT)
committer Michał Masłowski <mtjm@mtjm.eu>2014-09-03 14:30:21 (EDT)
commit96ca7ee67a36605a33de8d57eb8e8d3998bc6427 (patch)
tree07202c5fe7d366f50d9d17010f3bbf0a44c08ee8 /docs/future/old.html
parent4e8051dfaa0ba5617961481056eb7e79d7b50861 (diff)
parent9a321884379a71b5f0986fdfb97a2b6c5bdccd8a (diff)
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Merge libreboot-6b6.r20140903
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+<!DOCTYPE html>
+<html lang="en">
+<head>
+ <meta charset="utf-8">
+ <title>libreboot tutorials</title>
+
+ <style type="text/css">
+ body {
+ font-family: sans-serif;
+ font-size: 1em;
+ background: #fff;
+ color: #000;
+ }
+
+ </style>
+
+ <meta name="viewport" content="width=device-width, initial-scale=1.0">
+ <meta name="author" content="glugman">
+ <meta name="description" content="tutorials for libreboot, the reboot library.">
+ <meta name="robots" content="all">
+</head>
+
+<body>
+
+ <header>
+ <h1 id="pagetop">Development notes (old/obsolete notes)</h1>
+ <aside>For current notes, see <a href="index.html">index.html</a>.</aside>
+ </header>
+
+ <p>
+ These are old (obsolete) notes that mare kept because they might become useful again in the future.
+ </p>
+
+<hr/>
+
+ <h2>Contents</h2>
+ <ul>
+ <li><a href="#x60_native_notes">X60 native graphics initialization (backlight controls)</a></li>
+ <li><a href="#t60_native_notes">T60 native graphics initialization (backlight controls)</a></li>
+ <li><a href="#5320_kernel312fix">i945: 3D fix (based on 5927) for kernel 3.12+ on 5320</a></li>
+ <li><a href="#x60_cb5927_testing">i945/x60: coreboot 5927 testing (3D fix for kernel 3.12+ on replay code)</a></li>
+ </ul>
+
+<hr/>
+
+ <h1 id="x60_native_notes">X60 native graphics initialization (with backlight controls)</h1>
+
+ <p>
+ <b>
+ This is now obsolete. A better way was found (included in libreboot): <a href="http://review.coreboot.org/#/c/6731/">http://review.coreboot.org/#/c/6731/</a>
+ </b>
+ </p>
+
+ <p>
+ <b><i>Also check <a href="#5320_kernel312fix">#5320_kernel312fix</a> (to fix 3D on kernel 3.12/higher)</i></b>
+ </p>
+ <p>
+ <b>The fix below was done on 5320/6 (from review.coreboot.org) but should work just fine on later versions of 5320.</b>
+ </p>
+ <p>
+ Native gpu init + backlight controls! (Fn keys). Also confirmed on X60 Tablet (1024x768) and X60 Tablet (1400x1050)
+ </p>
+ <p>
+ <b>Add backlight controls:</b> in <i>src/mainboard/lenovo/x60/devicetree.cb</i>, change <b>gpu_backlight</b> to <b>0x879F879E</b>
+ </p>
+ <p>
+ That's all! <b>This has also been backported into libreboot 5th release (line 1233 in src/mainboard/lenovo/x60/i915io.c)</b>. GNUtoo (Denis Carikli)
+ told me about the register <b>BLC_PWM_CTL</b> and that you could set it to control backlight. I read that address using devmem2 while running the VBIOS:<br/>
+ <b># devmem2 0xe4361254 w</b>
+ </p>
+ <p>
+ The change is also included in libreboot 6.
+ </p>
+ <p>
+ When doing this, it gave back that value. The same trick was used to get backlight controls for T60 (see <a href="#t60_native_notes">#t60_native_notes</a>).
+ </p>
+
+ <h2>Further notes</h2>
+ <p>
+ Reading <b>0xe4361254</b> (address) in Lenovo BIOS always yields FFFFFFFF, even when writing to it (and writing to it doesn't affect brightness controls).
+ 'mtjm' on IRC found that the buttons (Fn keys) control /sys/class/backlight/acpi_video0 which has no affect on 61254 (BLC_PWM_CTL). He says
+ intel_backlight has different values and uses the register. devmem2 works, needs checking <b>lspci -vv</b> for where the memory is mapped,
+ which is different than on coreboot; mtjm found that it was 0xec061254 on his machine (X60 Tablet), and the register value is different too.
+ <b>This is relevant, because we still don't know how backlight controls are actually handled. We got it working by accident. We need to know more.</b>.
+ </p>
+ <p>
+ Intel-gpu-tools may prove useful for further debugging: <a href="http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/">http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/</a>
+ </p>
+ <p>
+ mtjm says 0xe4300000 is an MMIO region of the gpu (lspci -vv shows it), 0x61254 (BLC_PWM_CTL) is a documented register. Searching the kernel driver for backlight
+ shows that in intel_panel.c this register is used (there is an XXX comment about finding the right value, where recent kernels get it from.
+ </p>
+ <p>
+ What we want to do is calculate a good value, instead of setting it in devicetree.cb. mtjm says about backlight physics:
+ it has a light source , uses pulse width modulation (PWM) to turn it on/off, dimming is done by spending less time on.
+ <b>Note: this may not be correct; he says his understanding is based on how the Lenote yeeloong works</b>.
+ </p>
+ <p>
+ mtjm goes on to say, that the register specifies the frequency used for PWM in its depending on the GPU core frequency, so it
+ might be possible to calculate it without hardcoded laptop-specific values. Therefore, I am supposed to find out the 'display core frequency'
+ (mtjm says there might be a register for it; also, it might be in 5320 or the replay code) and the PWM modulation frequency.
+ https://en.wikipedia.org/wiki/Backlight#Flicker_due_to_backlight_dimming
+ </p>
+ <p>
+ phcoder (Vladimir Serbinenko) who is author of 5320 (review.coreboot.org) talks about 'duty cycle limit' and 'flickering frequency'.
+ </p>
+
+ <p><a href="#pagetop">Back to top of page</a></p>
+
+<hr/>
+
+ <h1 id="t60_native_notes">T60 native graphics initialization (with backlight controls)</h1>
+
+ <p>
+ <b>
+ This is now obsolete. A better way was found (included in libreboot): <a href="http://review.coreboot.org/#/c/6731/">http://review.coreboot.org/#/c/6731/</a>
+ </b>
+ </p>
+ <p>
+ <b><i>Also check <a href="#5320_kernel312fix">#5320_kernel312fix</a> (to fix 3D on kernel 3.12/higher)</i></b>
+ </p>
+ <p>
+ <b>The fix below was done on an earlier version of 5345 changeset (review.coreboot.org), but should work on the current version. it is included in libreboot 6</b>
+ </p>
+ <p>
+ <b>Add backlight controls:</b> in <i>src/mainboard/lenovo/t60/devicetree.cb</i>, change <b>gpu_backlight</b> to <b>0x58BF58BE</b>
+ </p>
+ <p>
+ Hold on! Check <a href="../index.html#get_edid_panelname">../index.html#get_edid_panelname</a> to know what LCD panel you have. This is important for the next step!
+ </p>
+
+ <h2>Supported panels</h2>
+ <p>
+ <a href="../index.html#supported_t60_list">../index.html#supported_t60_list</a>.
+ </p>
+
+ <p>
+ See <a href="#lcd_i945_incompatibility">#lcd_i945_incompatibility</a>.
+ </p>
+
+ <p><a href="#pagetop">Back to top of page</a></p>
+
+<hr/>
+
+ <h1 id="5320_kernel312fix">i945: 3D fix (based on 5927) for kernel 3.12+ on 5320</h1>
+
+ <p>
+ <b>
+ This is now obsolete. Merged in coreboot: <a href="http://review.coreboot.org/#/c/5927/">http://review.coreboot.org/#/c/5927/</a>
+ </b>
+ </p>
+
+ <p><b>This needs to be rewritten (or better organized, or deleted?)</b>. This is also now included in libreboot 6 (using the proper way, not the 7c0000 method which was a hack)</p>
+
+ <p>
+ <b>This was done on 5320/6 so far. The fix below is for 5320/6 which is now obsolete. This needs to be re-done for the latest version
+ of 5320. The fix below is (in practise) only for reference, therefore.</b>
+ </p>
+
+ <p>
+ See <a href="#x60_cb5927_testing">#x60_cb5927_testing</a> for the original (and current) fix, for the replay code. Now we want
+ to implement that on top of <a href="http://review.coreboot.org/#/c/5320">http://review.coreboot.org/#/c/5320</a>
+ which is the current code for native graphics initialization on i945.
+ </p>
+
+ <p>
+ src/northbridge/intel/i945/gma.c (using the 7c0000 hack) on 5320: <a href="dumps/5320_7c0000_gma.c">5320_7c0000_gma.c</a> (rename it to gma.c,
+ replacing the current one).
+ </p>
+
+ <p>
+ The above is a hack (as is the original). A better (more correct) method is implemented in later versions of 5927, so
+ that should also be adapted for 5320. For now, you can use the above fix.
+ </p>
+
+ <p>
+ The correct way to do it is to set gtt address to (end of stolen memory - gtt size), which is what later versions of 5927 do (successfully).
+ </p>
+
+ <p>
+ Here is some debugging output using intel_gpu_tools v1.2-1 (from trisquel repositories) using tool "intel_gtt":
+ </p>
+
+ <ul>
+ <li>
+ Trisquel 6. kernel 3.14.4:
+ <ul>
+ <li>with libreboot 5th release (using the 7c0000 gtt hack from 5927/3): <a href="http://paste.debian.net/104306">http://paste.debian.net/104306</a></li>
+ <li>with coreboot+vgarom: <a href="http://paste.debian.net/104309">http://paste.debian.net/104309</a></li>
+ </ul>
+ </li>
+ <li>
+ Trisquel 6. kernel 3.2.0-60 (from Trisquel repositories):
+ <ul>
+ <li>with coreboot (no vbios or native init): <a href="http://paste.debian.net/104341">http://paste.debian.net/104341</a></li>
+ </ul>
+ </li>
+ </ul>
+
+ <p><a href="#pagetop">Back to top of page</a></p>
+
+<hr/>
+
+ <h1 id="x60_cb5927_testing">i945/X60: Coreboot 5927 testing (3D fix for kernel 3.12+ on replay code)</h1>
+
+ <p>
+ <b>
+ This is now obsolete. Merged in coreboot: <a href="http://review.coreboot.org/#/c/5927/">http://review.coreboot.org/#/c/5927/</a>
+ </b>
+ </p>
+
+ <p><b>The latest version as-is (5927/11) has not been tested by me yet. Always boot with 'drm.debug=0x06' kernel parameter when testing this.</b></p>
+
+ <p>
+ This is the fix for 3D on kernel 3.12 and higher on i945 (ThinkPad X60 in this case). This is for the replay code.
+ Libreboot 5th release has a version of this backported already (based on 5927/3 using the '7c0000' hack).
+ </p>
+
+ <p>
+ <b>
+ The replay code is obsolete (see 5320 changeset on review.coreboot.org for better version
+ which supports more machines/screens, and then 5345 for T60). Information here for reference since that is where the fix was first applied.
+ </b>
+ </p>
+
+ <p>
+ Read the information on <a href="http://review.coreboot.org/#/c/5927/">http://review.coreboot.org/#/c/5927/</a>.
+ </p>
+
+ <p>
+ For historical purposes, here is a collection of IRC logs that once existed on this page, related to the issue:
+ <a href="dumps/kernel312_irc">kernel312_irc</a>.
+ </p>
+
+ <p>
+ PGETBL_CTL differs between VBIOS (-) and native graphics init (+).<br/>
+
+ - PGETBL_CTL: 0x3ffc0001<br/>
+ + PGETBL_CTL: 0x3f800001
+ </p>
+
+ <p>GTT (graphics translation table) size is PGETBL_save, max 256 KiB. BSM (Base of Stolen Memory) is given by the bios.</p>
+
+ <ul>
+ <li>5927/7: <a href="dumps/5927_7.tar.gz">5927_7.tar.gz</a> (GRUB graphics are correct now, and 3D still works)</li>
+ <li>5927/6: <a href="dumps/5927_6.tar.gz">5927_6.tar.gz</a> (GRUB graphics still corrupt, 3D/everything still works after GRUB)</li>
+ <li>5927/5: <a href="dumps/5927_5.tar.gz">5927_5.tar.gz</a> (GRUB graphics corrupt, 3D/everything still works after GRUB)</li>
+ <li>5927/3: <a href="dumps/5927_3.tar.gz">5927_3.tar.gz</a> (3D still works! kernel 3.14.4) - the '7c0000' hack</li>
+ <li>5927/2: <a href="dumps/5927_2.tar.gz">5927_2.tar.gz</a> (3D works! kernel 3.14.4) - the '7c0000' hack</li>
+ <li>
+ 5927/1 (didn't fix the 3D issue):
+ <ul>
+ <li><a href="dumps/5927_cbmemc">cbmem -c</a></li>
+ <li><a href="dumps/5927_crashdump">/sys/class/drm/card0/error</a></li>
+ <li><a href="dumps/5927_config">.config</a></li>
+ </ul>
+ </li>
+ </ul>
+
+ <p><a href="#pagetop">Back to top of page</a></p>
+
+<hr/>
+
+ <p>
+ Copyright &copy; 2014 Francis Rowe &lt;info@gluglug.org.uk&gt;<br/>
+ This document is released under the Creative Commons Attribution-ShareAlike 4.0 International Public License and all future versions.
+ A copy of the license can be found at <a href="../license.txt">../license.txt</a>.
+ </p>
+
+ <p>
+ This document is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See <a href="../license.txt">../license.txt</a> for more information.
+ </p>
+
+</body>
+</html>
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